Ten years ago most scientists did not take nanotechnology seriously, but now it is the talk of the scientific town. Large investments in nanofabrication (clean-room) facilities, the emergence of national research programmes in the United States and Japan, and a steadily increasing number of scientific papers appearing in Science and Nature have led to serious interest from the venture capital market. How things can change!
Nanotechnology (1 nm = 10-9 m) is at first sight nothing more than the logical extension of microtechnology, a step further toward miniaturization. Both names refer to dimensions of structures and have no scientific meaning like chemistry, physics, or biology. However, there are fundamental differences. Structures in the micro-domain can be made by photolithography, the technology that was developed for the microelectronics industry. The lower limit of current state-of-the-art photolithography is ~0.13 µm or 130 nm. The limiting factor for further miniaturization is the wavelength of light used to write structures in silicon. Both technological constraints and economic factors render it highly unlikely that photolithography will ever be able to create features smaller than 100 nm. For the microelectronics industry this means that, after 40 years, Moore?s Law can no longer be extrapolated.
Nanotechnology covers individual objects with dimensions between 1 and 100 nm. In physics these are considered to be small, in chemistry large, whilst for biologists this is the usual size of individual biopolymers and other important biological objects. Historically it was the scanning probe techniques such as scanning tunneling microscopy (STM), atomic force microscopy (AFM), and near-field optical microscopy that made it possible to see such nanostructures.
Not only would nanotechnology reduce the dimensions of existing microdevices, but more importantly it will produce objects and materials with fundamentally novel properties. The expectations of what nanotechnology will achieve in the future range from quantum computers, ultrastrong materials, self-cleaning fabrics, and information storage and retrieval to drug delivery to individual cells and implantable biosensors. Electronic and optical properties of structures below 100 nm are determined by quantum mechanics and such structures can no longer be described as classical continuous matter. In recent years the principles of nanoelectronics and nano-optics have been experimentally verified, and exciting results have been published and are currently debated.
There are two fundamentally different ways of fabricating nanostructures: top-down and bottom-up. The top-down technologies are usually an extrapolation of existing physical methods, such as lithography with electron or ion beams that have much smaller wavelengths than visible or UV light. Novel top-down technologies use sharp STM or AFM tips to write patterns by scratching, local deposition of materials, or even writing with (bio)molecules. The alternative bottom-up approaches use individual molecules as the building blocks and supramolecular chemistry to assemble these into larger structures. At some point in the development of nanotechnology the top-down and bottom-up approaches will merge into a variety of nanofabrication technologies.
The use of individual molecules, or even atoms, as the smallest possible building blocks of matter can be seen as the last stage of the development of construction technologies. It started many centuries ago when mankind began to construct artificial objects such as tools, houses, and bridges. In time this could be done with increasing control over function, precision, and miniaturization. The production technology for integrated electronic circuits that was developed in the past 30 years is probably the best illustration of this evolution. There is no reason to believe that the development of production technologies would stop at features of 100 nm. It will continue until we have reached the ultimate level of the smallest possible building blocks that we have, which are individual atoms and molecules. This is why nanotechnology is not just an extension of integrated circuits technology to smaller features. Nanotechnology will influence and in the end fundamentally change all our technological activities.
Just as during the past decade many scientists became convinced that nanotechnology would revolutionize our world, so the politicians have followed. When former US President Bill Clinton addressed Congress in 1999 and spoke about the importance of nanotechnology, defining it as the technology of the 21st century, nanotechnology became a part of the public domain. As a consequence, research budgets in the United States rose sharply, and other countries followed. In the 6th Framework Programme of the EU, nanotechnology will be one of the key areas.
Nanotech in the Netherlands: NANONED
With facilities for microelectronics at the three Technical Universities and world-class nanophysics and supramolecular chemistry groups, the Netherlands had an excellent starting position in the early 1990s. Groups at the Delft Institute of Microelectronics (DIMES, nanoelectronics) and MESA+ at the University of Twente (microsystems technology and supramolecular chemistry) were among the first to publish the preparation and properties of nanostructures. However, despite individual support by different branches of NWO (the Netherlands Organization for Scientific Research), there is, even in 2002, no national programme or center for nanotechnology in the Netherlands.
The Dutch scientific community realized that nanotechnology first of all requires state-of-the-art facilities. Both at DIMES and MESA+ existing clean rooms have, to some extent, been upgraded for nanofabrication. At the same time, members of the Royal Netherlands Academy of Arts and Sciences initiated a bottom-up discussion on a national programme for nanoscience and technology, and have now created NANONED. In this consortium, seven universities and TNO (the Netherlands Organization for Applied Scientific Research) have agreed on a national programme and have presented a plan to the Ministry of Economic Affairs. The plan involves investments in nanofabrication infrastructure by a further upgrade of existing clean-room facilities. This will secure access for all scientists in the Netherlands to nanofabrication tools and environment. The scientific programme consists of 11 selected areas, such as nanoelectronics, nanofluidics, bionanostructures, single molecule chemistry, physics and biology, nanofabrication and instrumentation, and nano-optics.
Individual research groups can participate in these areas on the basis of present competence and past performance. The preparatory stage of the programme is nearing completion, with industrial interest and participation being matched to the scientific ambitions and competences of the academic participants. This initiative is expected to lead to the (temporary) employment of more than 150 scientists, mostly at the PhD student and postdoc level, thus ensuring the formation of a critical mass of young researchers working in this new field and accustomed to interdisciplinary research.
Funding of the first phase, called Nanoimpuls, from the Ministry of Economic Affairs is expected before the end of 2002. Four subprogrammes have been selected and the first investments in infrastructure at Delft, Twente, and Groningen are being planned. Compared to other industrialized countries it is a ?late call?, but the bottom-up instead of a top-down process will hopefully have the advantages of self-assembly. In chemistry, self-assembly is highly efficient, prone to self-correction and leading to thermodynamically stable structures. Let?s hope that the same characteristics will be typical for NANONED. To quote a Belgian colleague: ?Even in a small country there must be plenty of room for a nanovalley?.